Polyether compositions useful as hydraulic fluids



United States Patent Office 3,524,816 Patented Aug. 18, 1970 3,524,816POLYETHER COMPOSITIONS USEFUL AS HYDRAULIC FLUIDS Hugh J. Hagemeyer,Jr., Alden E. Blood, and James D. Heller, Longview, Tex., assignors toEastman Kodak Company, Rochester, N.Y., a corporation of New Jersey NoDrawing. Filed Sept. 6, 1966, Ser. No. 577,185 Int. Cl. C09k 3/02 US.Cl. 252-73 4 Claims ABSTRACT OF THE DISCLOSURE A mixture of polyethershaving the general formulae l) HOCH CH O(CH CH O CHzCHZOH and 2) C Ha(CH3)zCHOH-CH2O CH2CH20)xH O H Ha wherein x is a whole number of from1-10, said mixture being useful as components of hydraulic fluids.

DISCLOSURE This application relates to methods and materials for theproduction of hydraulic fluids and hydraulic fluid components. Moreparticularly, this invention relates to polyether brake fluid componentsand brake fluids containing such polyether components.

In commercial brake fluids a very delicate balance of properties isrequired in order that the finished fluids meet the rigid requirementsset up by the Society of Automotive Engineers, hereinafter referred toas SAE. Because of this very delicate balance of properties thesubstitution of components which are ordinarily considered similar inchemical and physical properties for those used in previously knownbrake fluids often results in fluids which are unsatisfatcory accordingto SAE standards. Moreover, variation in the amounts of components alsofrequently results in fluids that are unsatisfactory according to SAEstandards.

Acceptable brake fluids are multi-component fluids which contain variousingredients to fulfill the function of a base lubricant, rubber swellinhibitor, viscosity improver, solvent, coupler, and antioxidant. Forthe most part, brake fluids have conventionally been mixtures ofalcohols and glycols in which minor amounts of other addenda areutilized to perform the specific functions such as those of anantioxidant. More recently the use of ethylene oxide adducts of ethyleneglycol has been accepted in the trade. Because of the viscosity problemspresented by use of the pure adduct, modified reaction products havebeen frequently utilized. One of the more common modifications is theutilization of some propylene oxide in the adduct. This results in arandom mixture which has improved viscosity characteristics. Theutilization of such adducts, however, is associated with the normalproblems involved with maintaining the delicately restrictive componentratios. Ever increasing demands for improved brake fluids havestimulated continued research efforts directed to meeting such demands.

It is therefore one object of this invention to produce novel polyetherbrake fluid components. Another object is to produce brake fluidcomponents which allow wider variation in brake fluid component ratios.Another object of this invention will be to provide brake fluidscontaining novel polyether components. Still another object of thisinvention is to produce brake fluids in which the specific fluidcomponents can ve varied to a greater degree and yet meet the rigid SAEspecifications. Still another object is to provide brake fluidcomponents which perform a dual function, more particularly to performthe function of a hydraulic fluid base lubricant and a rubber swellinhibitor. Still another object is to provide brake fluids havingimproved volatility characteristics and having excellent viscosityproperties.

These and other objects of the invention which will become apparenthereinafter are accomplished by the utilization of an ethylene oxideadduct of ethylene glycol containing a modifying amount of2,2,4-trimethylpentanediol-l,3. These adducts are generally prepared byreacting the trimethylpentanediol with the ethylene glycol and ethyleneoxide, particularly when these materials are present in the reactionmixture in a ratio of from 0.5-2.0 to 3.0-4.5 to 12-24 mole ratiorespectively. The reaction is generally catalyzed with an acid or basiccatalyst such as Lewis acids, sulfuric acid, benzene sulfonic acid,Raney nickel, sodium hydroxide, boron trifluoride and piperidine. It hasbeen found that trialkyl amines are particularly useful catalysts inthat their presence in the resultant product is not detrimental in brakefluids. The reaction is most preferably carried out in an inertenvironment such as under nitrogen gas and is normally conducted at anelevated temperature of about to 125 C., preferably at -115 C. At thattemperature range the reaction is normally complete within a two to fivehour period but usually is complete in about 3 /2 hours. The ethyleneoxide utilized in the reaction is most advantageously added gradually tothe reaction mixture and upon fiinal addition the reaction mixture isallowed to cool slowly and is then filtered.

The filtered product from the reaction scheme outlined above using atrialkylamine catalyst, e.g. triethylamine, has the advantage of beingsufliciently pure to obviate any further purification step. The productmay be used directly in brake fluids. The product comprises a mixture ofcompounds having the structural Formulas I and II HOCH CH O CH CH O CHCH OH oHmoH-cH-o orimouzowmcmopn wherein x is a whole number of from 0to 10, the average value of x being 3 to 4, and wherein the mixturecontains at least some polyethers of Formula I and at least some ofFormula II. The relative amounts of the polyethers of Formula I ascompared to those of Formula II generally range in the area of from 1-1to 2-1.

The following specific example is indicative of the general method whichcan be used in the preparation of the above described adducts.

EXAMPLE 1 To a 2-liter, 3-necked flask there was added 1 mole of2,2,4-trimethylpentanediol-1,3; 4 moles of ethylene glycol; and 40 ml.of triethylamine. The reaction vessel was then fitted with condensers,addition funnels, thermowell, and a stirring rod with watercooledbearing. The reactor was purged with N and the contents heated to 100 C.The addition of 18 moles of liquid ethylene oxide was then started andcarried out over a 3 /2 hour period. The reaction becomes exothermicafter the addition of ca. 75 ml. of ethylene oxide, and the reactiontemperature is controlled at 100-115 C. After final addition, thereaction product is allowed to cool slowly and is then filtered. Nostripping or additional processing is required before utilizing theproduct as a hydraulic fluid base lubricantrubber swell inhibitor.

The adduct mixture prepared from Example I is advantageously utilized inthe preparation of brake fluids The composition has the advantage ofperforming the dual functions of a base lubricant and a partial rubberswell inhibitor. It has been found that such preparation when mixed withother normal brake fluid components allows for wider variation in theratios of the individual compo- (butyl amines and tert butylhydroquinone) to produce a homogeneous, clear yellow fluid. This fluidwas subjected to evaluation as a hydraulic fluid under SAE 170Bspecifications for 70R1 heavy duty brake fluids. This fluid met allrequirements set forth by the specifications. The

nents. The total brake fluid has properties which fall well majorresults of this evaluation where as follows:

within the requirements for the two broad commercial TABLE 1classifications, 70R1 heavy duty and 70R3 extra heavy duty, i.e.classifications which meet the diiferent SAE Fluid i require ents max.

specifications according to those set forth in SAE procedure aNOB-Hydraulic Brake Fluids. With the exception of 5 22 vlscgslty(cclltistOkeSb-e i oint, F 157 145.5

speclalized military hydraulic fillldS, all brake flllldS fall Percentevaporation 212 12).- 73 so into these two commercial classifications.The main dilferlj ihfgg fi fig f ffk g; 8:

once in the speclficatlons for the classifications lies in the Irequirements for boiling point and flash point.

The blake fluids according f thls lllvel'ltloll comprise 3 Theseexamples that follow represent formulations se- Sllbstalltlal am011nt 0fthe YlP P i/ lected from a wide range of possible compositions of each yy OXlde adduct fliescllbed 111 comblnatloll fluid type. Each exampleshows variations in some of the Wlth VQIIOIIS alcohols Such as mlXed yand 116x311 a160- fluid components to illustrate the use of the newlydevelhels, diethylene y l monomethyl ether, heXylene g y oped baselubricant in either 70R1 or 7on3 brake fluids. dlethylene glycol, mlXedp y 316911015, l/ P Each formulation also contains corrosion andoxidation mixed y alcohols; and various Cellosolves, h inhibitors, e.g.the secondary amines and di-tertiarybutyl as ethylene glycol monoethylether, ethylene glycol monoh d i previously i d butyl ether, andethylene glycol monoisebutyl ether and The examples below indicate thatwhen components are esters such as y p i T held within the desiredranges indicated above all SAE concentration of the trimethylpentanedioladduct in the specifications are met.

Example N 0.

Fluid Type 70m 70R1 7on3 70R3 7on3 70R1 70R1 70m 70R1 70R1 PartsComponent:

TMPD/Ethylene glyool/ ethylene oxide. 33 Diethylene glycoL 282-methylpentnno 11 Alcohol 750 l 12 Ethylene glycol monobutyl ether 16Mixed amyl alcohols 2 Alcohol 3-58B 3 Finished fiuld properties:

F. viscosity (centistokes) Natural rubber swell (in) Percent evaporationl C4-C mixed primary and secondary alcohols. 1 Approximately 64% n-amyl,35% Z-Me-butyl, 1% n-butyl. 8 27% 2-methypentanol, 10% isobutanol,54%Alcohol 750.

various brake fluids generally varies from about 20% by weight to above39% by weight. For the heavy duty type hydraulic brake fluids it isgenerally advantageous to utilize the trimethylpentanediol adduct in aconcentration of from 21% by weight to about 31% by weight. For theextra heavy duty hydraulic brake fluids of the present invention it isgenerally advantageous to utilize a percentage range of about 25-30% byweight of the trimethylpentanediol adduct but higher concentrations canbe utilized such as 28-39% by weight with the total composition stillbeing capable of meeting the rigid SAE requirements. The brake fluidsalso contain a minor amount of antioxidant. While generally acceptedantioxidants can be utilized in the brake fluid components of theinstant invention it has been found that minor amounts, of up to 2%, ofa 2-1 mixture of di-n-butylamine and 2,5-di-tert-butylhydroquinonetogether with tri-n-butylamine forms an especially useful antioxidantfor the brake fluids of the instant invention.

The following examples illustrate various brake fluids of the instantinvention but are not intended to be limitations thereof.

EXAMPLE 2 There was mixed 27 parts of the TMPD/ethylene glycol/ ethyleneoxide adduct as described above, 35 parts diethylene glycol, 8 parts byweight 2-methylpentanol, 15 parts by weight ethylene glycol monobutylether plus minor amounts of corrosion and oxidation inhibitorsParticularly valuable brake fluids according to this invention have thefollowing compositions.

(A) Heavy duty hydraulic brake fluids (70Rl type):

25-35% by weight the polyether adduct mixture; 27-37% by Weightdiethylene glycol; 8-16% by weight Z-methylpentanol; 8-16% by weight C-C primary and secondary alcohols; 8-l6% ethylene glycol monobutylether; 0.ll.0% antioxidant.

21-31% by weight the polyether adduct mixture;

21-31% Alcohol 3-58B, an alcohol mixture of about 27% 2-methylpentanol,19% isobutanol, and 54% of various other C -C mixed primary andsecondary al cohols (Alcohol 750);

7-18% by weight ethylene glycol monobutyl ether; 31-41% by weightdiethylene glycol; 0.1-l.0% by weight antioxidant.

(B) Extra heavy duty hydraulic brake fluid (70R3 yp 28-39% by weight thepolyether adduct mixture; 31-41% by weight diethylene glycol;

20-40% by weight ethylene glycol monobutyl ether; 01-10% by weightantioxidant.

The invention has been described in considerable detail with particularreference to certain preferred embodiments thereof, but it will beunderstood that variations and modifications can be effected Within thespirit and scope of the invention as described hereinabove, and asdefined in the appended claims.

We claim:

1. A hydraulic fluid consisting essentially of (A) about 25-35% byweight of a mixture of polyethers having the general formulae 1 HOCH CHO CH CH O CH CH OH and (OHahCHCH--OHzO (CHgOHzO) Izli 1) HOCH CH O (CHCH O CH CH OH and (CH3)2CHCH( -CH2O (C HzCHzO );H

O H Ha wherein x is a whole number of from 1-10, the molar ratio of 1)to (2) being in the range of about 1/1 to 2/1,

(E) about 31-41% by weight diethylene glycol,

(C) about 20-40% by weight ethylene glycol monobutyl ether, and

(D) about 0.1-1.0% by weight antioxidant for inhibiting the oxidativedegradation of the hydraulic fluid.

3. A hydraulic fluid consisting essentially of (A) about 21-31% byweight of a mixture of polyethers having the general formulae 6 (1) HOCHCH O(CH CH O) CH CH OH and (CHs)zCHCH-( J-OH2O(CHzCHzO),H

OH CH3 wherein x is a whole number of from 1-10, the molar ratio of (1)to (2) being in the range of about 1/1 to 2/1,

(E) about 31-41% by weight diethylene glycol,

(C) about 8-18% by weight ethylene glycol monobutyl ether,

(D) about 5-25% by weight of C primary and secondary alcohols,

(E) about 5-25 by weight of mixed amyl alcohols,

and

(F) about 01-10% by weight antioxidant for inhibiting the oxidativedegradation of the hydrulic fluid.

4. A hydraulic fluid consisting essentially of (A) about 21-31% byweight of a mixture of polyethers having the general formulae wherein xis a whole number of from 1-10, the molar ratio of (1) to (2) being inthe range of about 1/1 to 2/1, (B) about 21-31% by weight of an alcoholmixture consisting essentially of (1) about 27 wt. percentZ-methylpentanol (2) about 19 wt. percent isobutanol, and (3) about 54wt. percent of C -C primary and secondary alcohols, (C) about 31-41% byweight diethylene glycol, (D) about 7-18% by weight ethylene glycolmonobutyl ether, and (E) about 0.1-1.0% by Weight antioxidant forinhibiting the oxidative degradation of the hydraulic fluid.

References Cited UNITED STATES PATENTS 2,425,755 8/ 1947 Roberts et a].3,062,747 11/1962 Fife et a1. 25273 3,324,035 6/1967 Nankee et a1.252-73 3,341,456 9/1967 Sawyer 252-75 3,346,501 10/1967 Boehmer 252-73LEON D. ROSDOL, Primary Examiner D. SILVERSTEIN, Assistant Examiner US.Cl. X.R. 252--77

